One day won't trash your entire week. But if you either not eat this weekend or continue to eat a lot - that WILL trash your entire week.
I try to just get right back on track the following day. Like yesterday - I ate horribly. But today - I'm back on track so far. I had a healthy breakfast, and plan to continue that through out the day.
I also try not to feel guilty about food and what I eat - because that connects feelings to food and eating and I don't want that. That leads to binging for me. I don't always succeed but I did today and yesterday. I don't feel guilty about what I ate. That was yesterday. Today is new